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Topic:Immunohistochemistry
Immunohistochemistry (IHC) is a laboratory technique used to visualize specific antigens in tissue sections of horses through the application of antibodies. This method allows for the detailed examination of the distribution and localization of proteins within equine tissues, providing insights into various physiological and pathological processes. IHC is employed in equine research to study a range of conditions, including infectious diseases, inflammatory responses, and neoplastic disorders. By utilizing specific antibodies that bind to target antigens, researchers can identify cellular and tissue changes, contributing to a better understanding of equine health and disease mechanisms. This page compiles peer-reviewed research studies and scholarly articles that explore the applications, methodologies, and findings of immunohistochemistry in the field of equine research.
Concurrent Small Intestinal Neoplasia And Large Colon Volvulus In A Standardbred Yearling. Large colon volvulus is a common, life-threatening cause of colic in horses. Gastrointestinal neoplasia is a rare cause of abdominal pain in young horses. A 1-year-old Standardbred colt presented with acute colic unresponsive to medical treatment. An exploratory laparotomy identified extensive gastrointestinal pathology, and euthanasia was elected due to a poor prognosis. Necropsy revealed a 360-degree volvulus of the caecum and large colon with adhesions, enterotyphlocolitis, and a well-circumscribed mesenteric mass arising from the small intestine. Histopathology in combination with immunohi...
Leptomeningeal dissemination of a poorly differentiated carcinoma involving the trigeminal ganglion in a horse: a case report. Neoplastic conditions involving cranial nerves are uncommon in horses and represent a significant diagnostic challenge. Leptomeningeal dissemination is a recognized mechanism of tumor progression in aggressive neoplasms but is rarely reported in this species. A 15-year-old mixed-breed horse with a history of periocular squamous cell carcinoma treated by enucleation three years earlier developed progressive neurological signs. Initial differential diagnoses included metastatic neoplasia and equine protozoal myeloencephalitis. Due to rapid neurological deterioration, euthanasia and necropsy were...
Central nervous system lymphoma and neurolymphomatosis in equids. Lymphoma affecting the central and peripheral nervous systems in equids is rarely reported. Objective: To describe the clinical presentation, neuroanatomical localization, laboratory and pathologic features, type of lymphoma, and outcome to further current knowledge. Methods: Fourteen equids (13 horses, 1 mule). Methods: Retrospective study. Medical records from a veterinary teaching hospital were reviewed (1993-2025). The inclusion criteria consisted of a definitive diagnosis of lymphoma of the nervous system. Data collected included signalment, neurologic findings, laboratory results, imagin...
Oxidative Stress and Immunomarkers in Equine Dermal Melanomatosis: Single-Case Comparison with Healthy Individual. Dermal melanomatosis is a common tumor in grey horses, characterized by cutaneous/subcutaneous lesions with metastatic potential. While clinically well-described, oxidative stress involvement remains poorly understood. This case report compared oxidative stress markers and antioxidant enzymes' activities in total protein extracts from melanomatosis lesions (grey horse) versus healthy control skin (black horse), alongside histopathology and immunohistochemistry, to correlate oxidative imbalance and tumor behavior. Melanomatosis tissue exhibited decreased antioxidant defenses confirmed by catala...
Penile and preputial pythiosis in Saudi Arabian horses: clinicopathological features and surgical outcomes. Pythiosis, caused by , is a chronic granulomatous disease of horses characterized by invasive, ulcerative, and pyogranulomatous cutaneous lesions. Involvement of the external genitalia is uncommon and remains poorly characterized, particularly regarding environmental exposure and treatment outcomes. This study aimed to describe the epidemiological pattern, clinicopathological features, diagnostic findings, and surgical outcomes of penile and preputial genital pythiosis in a hospital-presented horse cohort. Unassigned: A retrospective study was conducted on 123 horses presented with cutaneous u...
Mammary neuroendocrine tumor in a mare. A 10-y-old American Paint Horse mare was presented to the Equine Field Services at Virginia-Maryland College of Veterinary Medicine (Blacksburg, VA, USA) for evaluation of mastitis and a possible abscess in the right mamma. Histologic evaluation of a mammary biopsy revealed a densely cellular, infiltrative neoplasm with cells arranged in packets supported by thin stroma. In a neuroendocrine immunohistochemistry panel, the neoplastic cells did not immunolabel for neuron-specific enolase or synaptophysin, positively immunolabeled for chromogranin A, and had moderate scattered immunolabeling for ...
Equine Liver Histopathology. This review summarizes best practices for equine liver biopsy, including when to perform a biopsy, techniques for sample collection and handling, and strategies to optimize diagnostic yield. It discusses the interpretive framework used by pathologists, common diagnostic challenges, and prognostic scoring systems. Limitations such as sampling error and variability among observers are considered alongside ancillary testing, immunohistochemistry, and in situ hybridization. Emphasis is placed on the importance of communication between clinicians and pathologists to maximize diagnostic and prognost...
Derivation of Equine Mesenchymal Stem/Stromal Cells from Induced Pluripotent Stem Cells via the Neural Crest Pathway and Characterisation by Immunophenotype and Tri-Lineage Differentiation. Mesenchymal stem/stromal cells (MSCs) hold promise for treating different equine conditions but enter senescence during culture. Using induced pluripotent stem cells (iPSCs) to derive MSC-like cells (iMSCs) can increase cell availability and diminish the need for invasive and repeated tissue harvesting. While human iMSCs are intensively studied, research on equine iMSCs (eqiMSCs) is very limited and has focused on strategies for spontaneous differentiation to obtain these cells. The aim of this study was to obtain MSC-like cells from equine iPSCs (eqiPSCs) by directing their differentiation vi...
Immunohistological characterization of equine synovial tissue in metacarpophalangeal joints of different ages and osteoarthritis status. Synovial macrophages' role in equine osteoarthritis (OA) is not well understood, despite horses being a model for human degenerative joint disorders. Equine synovial macrophages' characterization is limited and age-related changes are not described. This study aimed to evaluate surface marker distribution and expression from potential synovial tissue macrophages in foals, adult non-affected, and OA-affected horses. Unassigned: Surface markers (CD14, CD16, CD206) were quantitatively evaluated on dorsal villous synovial biopsies from the metacarpophalangeal joint of foals (F), non-affected (cont...
Unusual, fatal neck cancer in a foal: immunohistological investigations and differential diagnosis. Neck masses may represent a diagnostic challenge for equine veterinarians, since they may involve different structures with a similar clinical appearance. Whereas neck masses in foals mostly result from non-neoplastic conditions, including various congenital abnormalities, neoplastic cervical masses have been rarely documented. This report describes the unusual case of a rapidly growing neck cancer in a four-month-old colt, resulting in a fatal outcome. Gross and immunohistological findings were most consistent with a poorly differentiated thymic carcinoma with sarcomatoid features and multifo...
Interleukins decrease epithelial protein and gene expression by K14 + CD105+ equine hoof progenitor cells. Background: Progenitor cell epithelial to mesenchymal transition (EMT) could impact healing in the epidermal-dermal junction of the equine hoof stratum internum (SI). The hypothesis of this study was that K14 + CD105+ equine hoof SI progenitor cells assume a mesenchymal phenotype in the presence of inflammatory interleukins in vitro.Methods: K14 + CD105+ progenitor cell percentages isolated from proliferative scarred (fibrous) and healthy SI were quantified. Decellularized matrix was prepared from and K14 + CD105+ cells localized in healthy SI. Gene expression (CD44, CD105, E-cadhe...
Persistence of Sarcocystis neurona and histopathology in horses with equine protozoal myeloencephalitis. Currently, little is known about the exact role of immunopathology in equine protozoal myeloencephalitis (EPM), including the ability to persist after anti-protozoal treatment. The main objectives of this study were to determine whether is present in the CNS in horses with EPM, including previously treated cases, and to evaluate the associated histopathology and immune response. For this study, control ( = 10) and horses with EPM ( = 9) were confirmed based on our inclusion criteria. Based on our preliminary data, we classified horses with EPM and clinical signs for >6 months as...
Nucleolar proteins nucleolin and nucleophosmin 1 differentially relocalize during equid alphaherpesvirus 1 (EHV1) infection. We investigated equine nucleolar proteins nucleophosmin 1 (NPM1) and nucleolin (NCL) during EHV1 infection to develop understanding of EHV1-nucleolar interactions. Equine NPM1 primarily localized throughout nucleoli whereas NCL accumulated in a peri-nucleolar ring and localized throughout the nucleoplasm. EHV1 did not notably affect NPM1 or NCL protein levels but did alter their subnuclear localization. NPM1 accumulated in EHV1 replication compartments and remained nucleolus-associated until very late infection stages, characterized by a kidney bean-shaped nucleus and round cell morphology. NC...
Equine genital and ocular squamous cell carcinomas: clinical, histopathological, molecular and viral characterization with proposed histopathological classification system. Equine squamous cell carcinomas (eSCCs) are common, and a proportion are likely induced by papillomavirus 2 (EcPV-2). Accurate prediction of clinical outcomes is challenging with no recognized prognostic criteria or consistent histopathological classification scheme for eSCC. The aims of this study were to histopathologically subtype a large case series of eSCCs (genital and ocular) and correlate them with p16 and HER-2 expression, equine papillomavirus infection status, and various clinical and histopathological parameters to predict tumour behavior and prognosis. One hundred and eighty-five...
Differential Expression of MITF, WNT3A, SLC7A11, and EDN3 in the Shoulder ‘Bider Marking’ of Dun Mongolian Horses. (1) Background: The "Bider marking" on the shoulder of the Dun Mongolian horse represents a unique pigmentation pattern, the molecular formation mechanism of which remains incompletely understood. This study investigates the differential expression and protein localization of pigment-related genes-specifically the core transcription factor , as well as , , and -in the skin. The analysis focuses on three distinct regions: the dark-colored area of the 'Bider marking' shoulder (BIDC), the light-colored area of the 'Bider marking' shoulder (BILC), and the non-Bider-marked shoulder area (NBIS). The...
Association between ultraviolet-related TP53 mutations and immune microenvironment in equine ocular squamous cell carcinoma. This study investigates the molecular and immune characteristics of equine ocular squamous cell carcinoma (eoSCC). Immunohistochemistry (IHC) and next-generation sequencing (NGS) were used to detect protein expression and TP53 mutations, respectively. T lymphocytes (CD3+), regulatory T cells (FoxP3+), B lymphocytes (CD20+), and macrophages (IBA-1+) were quantified. A total of 29 cases of eoSCC were evaluated, consisting of 3/29 carcinomas in situ (CISs) and 26/29 squamous cell carcinomas (SCCs). p53 positivity by IHC was detected in 19/29 cases while by NGS, 21 TP53 mutations were found in 13/...
Tissue-Engineered Osteochondral Allograft Versus Fresh Osteochondral Allograft: Comparable Cartilage and Subchondral Bone Repair in a 14-Month Equine Osteochondral Defect Model. Fresh osteochondral allograft (OCA) transplantation effectively repairs cartilage and subchondral bone; however, the persisting shortage of available donor OCAs and their short shelf-life make scheduling surgeries and meeting patient demand challenging. Attempts have been made to develop tissue-engineered solutions to address the limitations of OCA; nonetheless, these have failed to progress beyond the preclinical stage. Objective: To assess the safety and efficacy of a tissue-engineered osteochondral allograft (TE-OCA) as compared with equine OCA in an equine osteochondral defect model. Metho...
Clear cell squamous cell carcinoma in the third eyelid of a horse. Squamous cell carcinoma (SCC) is the most common ocular and periocular neoplasm of horses, typically arising from the limbus, third eyelid mucosa or mucocutaneous junctions of the upper and lower eyelids. Tumours are locally invasive, prone to recurrence and may rarely metastasize. Histological evaluation is required for definitive diagnosis and atypical SCC subtypes may be diagnostically challenging. Here we describe a clear cell SCC in the third eyelid of a 16-year-old female Quarter Horse. The red and invasive mass was surgically excised for histological evaluation. The lesion consisted of ...
Activation of the S100A8/A9 Alarmin Amplifies Inflammatory Pathways in Equine Ascending Placentitis. Ascending placentitis is a significant cause of equine pregnancy loss, yet the upstream inflammatory triggers are poorly defined. Recently, we identified S100A8/S100A9 (S100A8/A9) alarmins as potential upstream regulators in a chronic equine placentitis model. The current study aimed to determine whether this upregulation is sustained in the acute model and in clinical cases, and to elucidate the expression of their downstream inflammatory mediators. Using an experimental model, we quantified mRNA expression in acute ( = 5) and chronic ( = 6) placentitis induced by ssp. . We found mRNA expre...
Endothelial glycocalyx of equine intestinal vessels: electron microscopic and immunohistochemical imaging. To visualize the endothelial glycocalyx in equine intestinal vessels using electron microscopy and immunohistochemistry and to evaluate the impact of induced endotoxemia on its integrity. Unassigned: 6 healthy horses free of gastrointestinal disease were anesthetized with dexmedetomidine, ketamine, and diazepam and mechanically ventilated under isoflurane anesthesia. Jejunal venous tissue samples were collected after perfusion fixation with lanthanum nitrate before and 120 minutes after endotoxemia induced by IV administration of 30 ng·kg-1 Escherichia coli lipopolysaccharide. For transmissio...
Determining the timeline of gonadal and genital differentiation in male and female equine fetuses allows for early detection and intervention in malformations. Sexual differentiation in the equine fetus involves coordinated morphogenetic processes that shape both the gonads and the genital ducts. Although the formation of testes and ovaries has been relatively well documented, the temporal dynamics and morphometric patterns of the mesonephric (Wolffian) and paramesonephric (Müllerian) ducts remain insufficiently characterized. This study aimed to detail the timeline of gonadal and ductal differentiation in male and female equine fetuses during the critical developmental window between 60 and 80 days of gestation. Gross anatomical evaluation, histo...
Odontoblasts in Equine Hypsodont Teeth-How They Cope with Permanent Occlusal Wear. Horses' hypsodont (high-crowned) teeth face permanent dental wear. This is compensated for by a continuous eruption, which requires a high adaptability of odontoblasts; otherwise, the dental pulp would be exposed. Here, we report on how equine odontoblasts respond to the challenge of maintaining a high production rate of dentin. We analyzed CD90, a marker of odontoblastic differentiation, and nestin, a marker of mature odontoblasts, in equine pulpal tissue via immunofluorescence. For comparison, we examined the hypselodont (ever-growing) incisors and brachydont (short-crowned) molars of rats. ...
Differential Expression and Analysis of TBX3 Gene in Skin Tissues of Dun Mongolian Horses with and Without Bider Markings. (1) Background: The dun coat color, a wild-type phenotype in horses characterized by pigment dilution and primitive markings, is regulated by . This study explored the expression and localization of in the Bider marking (a primitive mark unique to the shoulder of horses); (2) Methods: We compared skin tissues from Bider-marked and non-Bider dun Mongolian horses. Samples were collected from the Bider area (dark-colored/light-colored shoulder), dorsal midline, and croup. Histological staining, qRT-PCR, and Western blotting were used to analyze pigment distribution and expression at mRNA and pr...
Post-surgical seroreversion in a case of equine cutaneous leishmaniosis by Leishmania infantum. Equine leishmaniosis, caused by Leishmania infantum and transmitted by infected sand flies, has been increasingly reported in Europe, although clinical and immunological data remain scarce. We describe a 10-year-old mare from southern Spain presenting with periocular nodular lesions. Histopathology and immunohistochemistry confirmed granulomatous dermatitis with intrahistiocytic Leishmania amastigotes. Additionally, Leishmania infantum DNA was detected in paraffin embedded skin biopsy. Following surgical removal of the lesions, sequential serological monitoring using enzyme-linked immunosorben...
Detection of vasculogenic mimicry in equine ocular, oronasal, and genital squamous cell carcinoma. Squamous cell carcinoma (SCC) is the most common malignant tumor disease in horses. It predominantly affects the ocular, oronasal, and anogenital region. Equine SCC is difficult to treat, also because important aspects of SCC development and metastasis are still unclear. We previously provided evidence that equine SCC cells can adopt a stem cell-like phenotype as a hallmark of malignant progression. Here, we investigated whether equine SCCs harbor endothelial-like tumor cells that form an alternative network of pseudo-vessels better known as vasculogenic mimicry (VM). Following histopathologic...
Listeria monocytogenes septicemia in foals: A case series (1986 to 2024). Listeriosis is caused by , a Gram-positive, facultative anaerobic, intracellular rod bacterium that can infect a wide variety of species. Listeriosis occurs in a diverse range of domestic and wild animals but is most commonly a disease of ruminants. Clinical signs include meningoencephalitis, typhlocolitis, septic arthritis, and abortions. Listeriosis in horses has been reported in several countries but is an uncommon diagnosis. This report describes clinical, bacteriological, histopathological, and immunohistochemical findings in 6 foals with neonatal septicemia from which was isolated. Key ...
Sodium-glucose transporters SGLT1 and SGLT2 in equine renal, hepatic and pancreatic tissue. Insulin dysregulation is a hallmark of equine metabolic syndrome (EMS), and in recent years, pharmacological treatment with sodium-dependent glucose transporter 2 inhibitors (SGLT2i) have shown promise in reducing the risk of hyperinsulinemia-associated laminitis in horses diagnosed with EMS. In humans and laboratory animals, this transporter protein is responsible for the majority of renal tubular glucose reabsorption, however, the presence of this and the related sodium-dependent glucose transporter 1 (SGLT1) have not yet been studied in equine kidneys. Additionally, studies in humans and la...
Cyclooxygenase-2 and von Willebrand factor-an immunohistochemical study of the equine foot with and without laminitis, post-mortem perfused with paraffin oil. Equine laminitis is a complex and potentially fatal disease characterized by severe vascular and inflammatory alterations within the equine foot. This study aimed to develop immunohistochemistry (IHC) protocols for the detection of cyclooxygenase-2 (COX-2) and von Willebrand factor (vWF) in equine feet with and without laminitis, post-mortem perfused with paraffin oil. Unassigned: A total of 12 equine forelimbs from 8 horses were utilized in this study, divided into two study cohorts: one with laminitis and the other as a non-laminitis control. To develop the IHC protocols thoroughly, the tiss...
Beneath the surface: gut microbes, cyathostomins and resident immune cells – Characterising the baseline. Cyathostomins are the most prevalent and currently considered the most pathogenic gastrointestinal nematodes in horses. Their life cycle includes an encystment phase within the large intestinal mucosa, where up to 90 % of the total worm burden resides. Clinical disease ranges from chronic protein-losing enteropathy to acute, sometimes fatal, typhlocolitis. Despite their significance, the ecological interplay between cyathostomins, the host immune response, and the gut microbiota remains poorly understood. To our knowledge, this is the first study to investigate these interactions at the mucos...
Cannabinoid and cannabinoid related receptors in fibroblasts, inflammatory and endothelial cells of the equine hoof with and without laminitis: novel pharmacological target. Evidence suggests that the endocannabinoid system (ECS) is crucial for regulating inflammation, cell proliferation and pain. The ECS is composed of cannabinoid receptors such as type 1 (CBR1), type 2 (CBR2) and GPR55, endocannabinoids and enzymes. Proteins of ECS have previously been localized in the epidermal cells of the horse hooves. Given the physio-pathological role and cellular distribution of the ECS across species, the authors hypothesized that cannabinoid receptors are expressed within the inflammatory cells, fibroblasts and endothelial cells of the equine hoof laminae, going beyond t...
